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Ed Blough
11-13-2007, 10:44 AM
Hi
I have a couple of quick questions.
Our electric stove is shot so we have to replace it. The old stove was a drop in which is hard wired. The new stove is a slide in which has a pigtail and plug.

Now my questions,
The house was built in 79 so I believe the supply wire is aluminum when I install a plug for the new stove is there anything I should do special? I thought I remember something about an anticorrosive dope or something.

I was even thinking of using cable terminals and solder them to insure a solid contact with the plug terminals?

When I ordered the stove they wanted to know which pigtail to install. A three prong or four. Since the wiring is older I doubt they had the ground wire (fairly new code) so I went with the three. Would I have been smarter to go with the four prong plug either leaving the ground empty or connected to the common?

Also the present stove breaker is 60 amps. I think new stoves only require 40 amp circuits would it be smart to change the breaker?

Lastly I will have to cut the cabinet since the new stove goes to the floor. Is there anything I need to keep an eye out doing this?

Many questions but I appreciate any help offered.
Ed

Brad Sperr
11-13-2007, 12:57 PM
It's funny you should mention this, because I'll be doing the same thing as you in a week or so. LOML and I just bought a new house and we are replacing the drop-in range w/ a range/stove combination.

If your old range was hard-wired and your new stove has a pigtail plug, it sounds like you'll need to install a new receptacle in the cut-out where your stove will go. Is it just the service entrance to the house that's aluminum (which is very common) or is it the house wiring, as well? If the wiring in the house is aluminum, be sure that you get a receptacle that's rated for aluminum wiring. I know that proper tightening at receptacles is a major issue with aluminum wiring also, due to the pronounced expansion and contraction upon heating. There may be some additional steps to prevent corrosion as well.

As far as making the cut-out for the new stove goes, I'm just gonna "grip it and rip it" and then reframe the cabinet after the fact with some furring strips and pocket screw (we'll probably install new cabinets in the future).

You may want to move this post to the off-topic forum. Good luck and let me know if you gather any pointers.

Ed Blough
11-13-2007, 1:15 PM
It's funny you should mention this, because I'll be doing the same thing as you in a week or so. LOML and I just bought a new house and we are replacing the drop-in range w/ a range/stove combination.

If your old range was hard-wired and your new stove has a pigtail plug, it sounds like you'll need to install a new receptacle in the cut-out where your stove will go. Is it just the service entrance to the house that's aluminum (which is very common) or is it the house wiring, as well? If the wiring in the house is aluminum, be sure that you get a receptacle that's rated for aluminum wiring. I know that proper tightening at receptacles is a major issue with aluminum wiring also, due to the pronounced expansion and contraction upon heating. There may be some additional steps to prevent corrosion as well.

As far as making the cut-out for the new stove goes, I'm just gonna "grip it and rip it" and then reframe the cabinet after the fact with some furring strips and pocket screw (we'll probably install new cabinets in the future).

You may want to move this post to the off-topic forum. Good luck and let me know if you gather any pointers.

Brad the stove supply line is aluminum. All the heavy lines are aluminum and the rest of the house is copper. I think this was code in 78-79.

I have since posted this question in off topics like you suggestted. Can you tell me more about the receptacle? I didn't know there were special ones for aluminum. Also do you know anything about the anticorrosive paste?
Thanks for responding to my questions

Brad Sperr
11-13-2007, 1:31 PM
Hi Ed,

The receptacles that are rated for aluminum wiring should be marked with an "ALR" on the receptacle body. I would follow the instructions that come with the receptacle as far as applying an anti-corrosive grease, because I've heard some manufacturers recommend it and others don't.

I don't think it would be necessary to undersize the breaker when you install the new stove. I would just match it to the gauge of the wire.

Steve Leverich
11-13-2007, 3:01 PM
Ed, pretty much every receptacle these days is rated "Cu/Al", which stands for Copper (Cupric, hence the Cu) and Aluminum.

Things to be careful of when using aluminum wire in a Cu/AL rated range receptacle -

1 - Aluminum needs to be tightly connected so make sure the screws that hold the wire in the receptacle are TIGHT (but not stripped) - this is because Aluminum expands/contracts with temperature changes more than Copper does, and loose electrical connections will heat up causing failure.

2 - the anti-corrosive you're looking for - one commonly used brand is called NoAlOx, short for No Aluminum Oxidation. You just spread it on the bare end of the aluminum wire, insert in the terminal, and tighten.

Things in general -

ALWAYS, ALWAYS turn off the circuit breaker to the circuit you're working on, and VERIFY that it's off before touching ANY part of the wiring.

Check to make sure your hard-wired connection is already in a box, and that the wires aren't too short to connect to a receptacle - the wires should be either insulated with different colors (Black, Red, White, Green or bare) or at least taped with colored electrical tape (called "phase tape" by electricians)

If your in-wall box isn't big enough for the receptacle you need (50 amp range outlet) you will need to get a different box so the receptacle will fit.
In most cases, this will mean getting an "old work" box - these are designed with special built-in fasteners that grip the surrounding wallboard. You may need to enlarge the hole in your wallboard depending on what size box was originally installed, but the cover for the new box will cover any SMALL gaps between box and wallboard.

When you've determined what you need to change things over, I would buy ALL the parts at the same time/place to make sure they're compatible - the wall box, 50-amp receptacle, box cover, 50-amp range pigtail (get one long enough so you can plug in the stove when it's NOT in final position) and of course, a small tube of NoAlOx (if your store doesn't have that brand, ask for an equivalent, and HOPE that your clerk is more than half a notch beyond asking if "you want fries with that??!?")

Older stoves only used a 3-wire system - two "hot" phases of 120 volts each (sum 240 volts, since they're 180 degrees out of phase) and a neutral/ground. Newer systems use 4 wires - the extra wire is a separate ground. Your older wiring is likely only 3-wire; if so, and your new stove has 4, you can (I think) hook the ground (4th wire) to the neutral (white wire, if it was done correctly) inside the box. Reason for the (I think) - even though I'm licensed as an electrician in order to do my job in industrial instrumentation, I do NOT install stoves for a living - there may be a code-related reason this is not acceptable - I will check with some of our "real" electricians on this next time I see them (probably tomorrow) and get back to you on this.

That size aluminum wire is very hard to bend, so it will be difficult to install the receptacle in the box - it's likely you will need to re-strip the old wire to make it short enough to fit inside the box. Things to be careful of are NOT nicking the wires when stripping, and NOT bending the wires right where they're stripped - otherwise, you may break the wire where the insulation stops - this, because it's tricky to strip wire WITHOUT accidentally nicking the wire. If you bend the wire and it IS nicked, it may break at that point.

Hope this helps - I'll try to get the rest cleared up in a day or two... Steve

Oh, almost forgot - do NOT solder ANYTHING in this system - solder MELTS at too low a temperature, and is strictly FORBIDDEN in electrical connections. Approved connections are screw terminals or wire nuts.

Steve Leverich
11-13-2007, 3:33 PM
Just re-read this thread, and realized that you and Brad had covered most of what I added - sorry for any duplication.

60 amps seems kinda large for a stove breaker, they're usually 50 - but breakers are, among other things, sized to protect the WIRE from overheating so from that standpoint, it might be good to double-check your aluminum wire size vs. breaker size. Also, if your new stove wants a 40 amp circuit it might be a good idea to use a smaller breaker - it just can't be LARGER than the wire can handle, and of course the breaker's terminals need to be large enough to ACCEPT the wires - if you change this end, you will also need to use the NoAlOx on those connections as well... Steve

Brian Elfert
11-16-2007, 4:25 AM
My memory may be foggy, but aren't three wire stove/dryer outlets missing the neutral, not the ground?

Dryers and stoves used to use the ground as a neutral for the 110 volt stuff like the dryer motor, but the NEC was changed and now any appliance that has both 110 volt and 220 volt needs a neutral and thus a four wire receptacle.